This most-improved microscope was manufactured by W. & S. Jones. His company was established at 30 Holborn Street in London, as marked on one of the three folding legs on which this device is based. It rests on a tall cylindrical column on which the square axis is articulated in its upper part with a compass-type mechanism, on which the optical elements of the apparatus are held and moved.

The plano-convex mirror moves in a semicircle supported by an axis that moves vertically by means of a mechanism with two lateral screws. The optical condenser, supported on a fixed axis, moves vertically, approaching the stage. This is moved, also vertically, by means of a rack and is moved laterally by a toothed wheel mechanism. Finally, the lens is moved back and forth via a knurled shaft on a rack.

The stage has as many holes on its three sides that can accommodate tweezers, a porthole condenser and other accessories. The mahogany case has holes to accommodate six objectives, two of them Lieberküh system, an ivory case for small circular crystals, two rectangular pits with four-hole bone slides and a housing for the external condenser.

History of the “Most-Improved” model of W. & S. Jones.

William and Samuel Jones designed mainly portable compound microscopes of the botanical type and also models of greater size and complexity. Initially they made a “botanical” model with three magnifying glasses that rotated on an axis, overlapping to get more magnification. It was a crude, small, low-power instrument. Later they bought from George Adams the rights to his book “Essays on the microscope” published in 1787 and containing engravings and diagrams of microscopes. This would be used by Jones to make these models from 1795 on, which were essentially small botanical microscopes.

In 1798 they began to manufacture this larger model, “Most Improved”, derived from the model of the same name designed by George Adams. It was manufactured in two formats, a smaller one with a fixed mirror and a larger one, with the mirror moving along the axis of the microscope. This was the model-type of the pre-achromatic era that still continued to be manufactured with achromatic objectives.4